Porous core rod

ABSTRACT

A blow slot equipped core rod assembly which incorporates a porous metal wall portion. Internal conduit means in the assembly permit a fluid (such as air, or the like) to be supplied to said blow slot (when open) and to such porous metal wall portion under superatmospheric or under subatmospheric pressure. The core rod is particularly useful in the manufacture of multilayered thermoplastic containers by injection blow molding procedures.

RELATED APPLICATION

This application is a continuation-in-part of my earlier filed U.S.application Ser. No. 608,178 filed Aug. 27, 1975 now abandoned which inturn is a divisional application of my prior U.S. application Ser. No.448,191 filed March 5, 1974, now abandoned.

BACKGROUND OF THE INVENTION

Various techniques for molding hollow plastic articles and containersare known in the prior art. By one of these techniques, multiwalledcontainers may be produced by an injection blow molding procedure. Sucha container may, for example, incorporate an inner wall or layercomprised of a thermoplastic resin having barrier properties (e.g. asrespects water vapor or carbon dioxide transmission) and an outer wallor layer comprised of a thermoplastic resin having structuralproperties. In accordance with one such technique, a preformed liner ofthermoplastic material which can, for example, be comprised of two ormore layers or walls of differing thermoplastic resins is positionedover a core rod. The core rod is then positioned in the cavity of aninjection molding zone and an injectable heated thermoplastic resin isinjected into such cavity to form a composite preform or parison whereinthe liner comprises the liner wall portion thereof. The compositepreform on the core rod is removed from such injection mold cavity andis positioned next in the cavity of a blow molding zone. Fluid pressureis exerted on the preform between the preform and the core rod to anextent sufficient to make the preform expand into contact with adjacentwall portions defining the blow mold cavity which results in theproduction of a blown container. The blown container is removed from theblow mold cavity and the blown container is then separated from the corerod.

In endeavoring to practice such one technique at commercially acceptablerates so as to produce commercially acceptable product containers,problems have been experienced because of a tendency for the liner toexperience creasing during formation of the preform apparently due to avariety of factors many of which appear to be associated withorientation and/or liner size variations in relation to an adjacent corerod. In practice such creasing tendency results in a significantpercentage of product containers being formed of substandard quality.

Because of price and cost considerations, it is necessary for commercialpurposes to have little or no rejects in a plastic manufacturingoperation. Hence, in order to produce by such one technique high qualitycontainers at commercial rates with few rejects, it is necessary to havean improvement in the practice of such one technique.

BRIEF SUMMARY OF THE INVENTION

By the present invention, there is provided a blow slot equipped corerod assembly which incorporates a porous metal section in the headportion thereof and which also incorporates conduit means for passingair through the blow slot thereof as well as from and through suchporous metal section thereof.

Such a core rod assembly permits one to reduce air (or gas) pressurebelow atmospheric within the core rod during placement of a mating lineron the head portion thereof thereby holding the liner closely over thecore rod against further movement and without air being entrainedbetween the core rod and the liner. In this manner, during subsequentprocessing operations as briefly above described, the liner is moreevenly temperature conditioned than previously and creasing is minimizedor even completely eliminated from such a cause as, for example, linershrinkage during preform injecting in the molding operation.

An object of the present invention is to provide an improved core rodassembly for the injection blow molding of hollow plastic articles,particularly multiwalled containers which permits one to overcome theabove described problems of the prior art.

Another object of the present invention is to provide a novel core rodhead subassembly for an injection blow molding process and apparatus.

A further object is to provide a novel core rod head subassembly blowcore which permits a more uniform temperature conditioning of a linerpositioned thereover than was previously available in the art.

Various other objects, aims, purposes, features, uses and the like forthis invention will become apparent to those skilled in the art from thefollowing detailed description taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic top view, partially in section, of a four stagerotary injection blow molding machine illustrating the field of use fora core rod assembly of the present invention;

FIG. 2 is a schematic vertical sectional view of the rotary injectionblow machine of FIG. 1 taken along the line II--II thereof;

FIG. 3 is a detail-type longitudinal cross-sectional view through oneembodiment of a porous core rod assembly of the present invention;

FIG. 4 is a fragmentary sectional view horizontally taken through apreferred embodiment of a four stage rotary injection blow moldingmachine of the present invention which utilizes a blow slot equippedcore rod assembly which incorporates a porous metal wall portion;

FIG. 5 is a vertical sectional view taken generally along the line V--Vof FIG. 4;

FIG. 6 is a sectional view transversely taken generally along the lineVI--VI of FIG. 4;

FIG. 7 is a view similar to FIG. 3 but illustrating an alternativeembodiment of a porous core rod assembly of the present invention;

FIG. 8 is a view similar to FIG. 3 but showing a further alternativeembodiment of a core rod assembly of the present invention;

FIG. 9 is a fragmentary longitudinal sectional view through a core rodassembly of the prior art illustrating certain problems experienced inthe prior art;

FIG. 10 is a fragmentary vertical sectional view through a prior artcore rod assembly illustrating certain prior art problems;

FIG. 11 is a diagrammatic representation of a controlled arrangement ofthe type utilized for controlling and operating a four stage rotaryinjection blow molding machine in a simplified format;

FIG. 12 is a flow sheet illustrating one embodiment of the process stepsequence employed in using a porous blow slot equipped core rod assemblyin an injection blow molding operation.

DETAILED DESCRIPTION

Illustrated in FIGS. 1 and 2, for example, is a schematic presentationof one embodiment of a four stage rotary injection blow molding machine10 into which a plurality of the core rod assemblies of the presentinvention may be incorporated. The rotary injection blow molding machine10 incorporates a square shaped (or sided) indexing platen (or turret)12 mounted on a shaft 14 which is equipped with a Ferguson drive 16having a clutch brake and timing assembly. The drive assembly 16 and themachine 10 are provided with the usual and conventional instrumentation,timing circuits, safety features, and the like for automatic andcontinuous operation of the machine 10. The machine 10 is provided withfour operational stations, i.e., a liner feed station A, a preforminjection station B, a blow molding station C, and a product removalstation D. Each side of the platen or turret 12 is provided with anequal plurality of core rods 18 which are functionally interconnectedwith fluid conduits 20. Optionally, the platen 12 can be fitted withintermediate heat transfer conduit (not shown) for core rod 18temperature control. Preform injection station B is provided with splitinjection molds 22, and blow molding station C is provided with splitblow molds 24. The molds 22 and 24 are provided with intermediate heattransfer conduits (not shown) as are known to those skilled in the art.

In operation, the platen 12 is set to rotate intermittently through 90°per cycle of indexing at a setable time interval dependent on suchvariables, for example, as injection time, blow time, molded partremoval, and the like.

At the liner feed station A, individual liners 26 from a liner magazineand feeder assembly 28 are positioned over one set of respectiveindividual core rods 18. Thereafter, the split molds 22 and 24 are fullyopened and the platen or turret 12 is raised by means of a verticalmovement of a vertically displaceable machine platen (not shown). Theplaten 12 is then caused to rotate through 90° by the drive 16, therebyto move the liner equipped core rods 18 to station B. Generally, thelower portion of the molds 22 and 24 are immoveably positioned, and theassociated respective mating upper portions thereof are mounted to thevertically displaceable machine platen (not shown). After completion of90° indexing step, the platen or turret 12 is caused to descend by thevertically displaceable machine platen (not shown) while concurrentlythe upper halves of the molds 22 and 24 are caused to close about therespective core rods 18.

At injection station B, a hot injectable plastic material 30 is injectedthrough the injection nozzles 32 about the liner covered core rods toform composite preforms 34 within molds 22, the plastic being injectedin the space between each individual liner 26 and the adjacentrespective cavity wall surfaces 36 of the individual injection molds 22.

Thereafter, the split molds 22 and 24 are again fully opened, and theplaten or turret 12 is again raised by the machine platen (not shown)and another 90° rotational indexing step of turret 12 is undertaken.After completion of such indexing step, the platen 12 and the moldhalves 22 and 24 are permitted to descend to an operational position bythe vertically displaceable machine platen (not shown). Thus, theindividual composite preforms 34 are positioned within the respectiveblow molds C. A pressurized fluid, typically compressed air, isintroduced into conduit 20 and discharged through blow slots (not shownin FIGS. 1 and 2) of the individual core rods 18 to cause the individualcomposite preforms to be expanded and to assume the shape of theoverlying cavity surfaces 38 of the blow molds 24, thereby formingcomposite multiwalled blow molded containers 40.

Thereafter, through the action of the vertically displaceable machineplaten (not shown) the split molds 22 and 24 are again fully opened, andthe platen 12 is again raised. Machine platen 12 now indexes another 90°which brings the thus blown containers to the product removal station D.After the vertically displaceable machine platen is again lowered(closing the split molds 22 and 24 and bringing the platen 12 into anoperative position), the containers 40 are removed typically by amechanical means and the containers 40 are allowed to drop onto aconveyor assembly 42 or the like for conventional subsequent inspection.filling, packaging and the like (not shown). Those skilled in the artwill appreciate that the above-described sequence of operations for oneset of core rods is also experienced by each of the other three sets ofcore rods on respective other sides of the turret 12. Such anoperational sequence is typical of the stages of operation of a fourstage rotary injection blow molding machine.

Referring now to FIG. 3, there is seen illustrated one embodiment of acore rod assembly 50 of this invention having a head member 52 and abody member 54. The head member 52 incorporates a rod member 56, adisc-shaped base member 58, a tubularly-shaped core pin (or rod) member60, and a core pin (or rod) support member 62. The rod member 56 isthreaded at 1 and 64 thereof and is centrally affixed at its other end66 to base member 58. Orifices 68 are provided through base member 58which has cylindrical, peripheral or circumferential outerwall portions.

The tubularly-shaped core pin member 60 is formed with tapered innerwallsurfaces 70 which converge with increasing distances from base member58. Member 60 is mounted on base member 58 and extends co-axially with,but in a direction opposite from, the rod member 56.

The core pin member 60 has two sections, a base portion 72 of a solidmaterial, such as hardened tool or stainless steel, and a forward faceportion or section 74 formed of a porous material (i.e., one having amultiplicity of discreet passages formed therein during fabricationthereof, such as, for example a two (2) micron porous stainless steel,or the like, with the base portion 72 being mounted about thecircumference of base member 58, and with the face portion 74 beingsecured to the base portion 72, all by any convenient means, such aspress fitting, brazing, or the like. The core pin support member 62 isgenerally and preferably formed of a material exhibiting excellent heattransfer properties, such as copper, copper alloy, or the like. Supportmember 62 has a base section 76 which is centrally secured, as bybrazing or the like, to the base member 58 in a co-axially alignmentwith the rod member 56, a helically-shaped or surfaced intermediatesection 78, and an end section 80. The threaded or helically flangedportion of the intermediate section 78 is formed with cylindricallyextending flattened land portions which are arranged to be in intimatecontact with mating tapered innerwall surface portions 70 of the corepin member 60. The end section 80 of support member 62 is coterminouswith the end face of portion or section 74 of the core pin member 60.

The body member 54 is comprised of a cylindrically-shaped stem portion82 and a cylindrically-shaped sleeve portion 84. Body member 54 isformed with a centrally disposed cylindrical passageway 86. The endsection of the stem portion 82 opposite the sleeve portion 84 isprovided with counterboard orifices 88 and 90, orifice 88 being deeperand having a smaller diameter than in the case of orifice 90. The sleeveportion 84 is formed with a cylindrical chamber 92 which is co-axialwith passageway 86 and chamber 92 has a countersunk shouldered portion94. The rod 56 of the head member 52 is extended through the passageway86. A nut 98 is rotatably mounted on the threaded end portion 64 of therod member 56, and is spaced apart from the inner shoulder wall surfaceof the counterboard orifice 90 when head member 52 is fully nested inbody member 54 in the configuration shown by the solid lines in FIG. 3.A spring 96 is compressed between the shouldered surface 94 of the bodymember 54 and the rim edge of nut 98 in the cavity 88 so as toyieldingly bias head member 52 in a fully nested engagement with thebody member 54 (as shown in FIG. 3 by solid lines). The spacialrelationship between the rod 56 and the orifices 90 and 98 with thepassageway 56 together with the spacial relationship between the outersurface of the base portion 72 of the core pin member 60 and the innersurface forming the chamber 92 forms a passageway or a channel for afluid expanding medium (such as a gas like air) charged to the core rodassembly 50 through the orifice 90.

The head member 52 is caused to move axially forwardly relative to thebody member 54 in the direction indicated by the arrow A in FIG. 3 by amechanical means (not shown) associated with the platen 12 and appliedgenerally axially against the nut 98. When this means is applied, headchamber 52 becomes moved to a location illustrated by the dotted linesshown in FIG. 3 at which location a compression fluid can pass throughthe assembly 50 from orifice 90 and out from the annular space definedbetween such respective head and body members 52 and 54. Removal of theapplication of such mechanical means from nut 98 causes the head member52 to retract into the body member 52 by the effect of the compressiveforce of the spring 96 against the nut 98 threadably mounted on the rodmember 56. Additionally, as a result of the orifices (not detailed) inthe porous metal of the face portion or section 74 of the head member 52being present, a gaseous medium can pass through such porous faceportion or section 74.

The core rod assemblies 50 can be utilized in the four stage rotaryinjection blowing machine by using the core rod assemblies 50 in themachine 10 in place of the core rods 18 with the machine 10 beingmodified as herein described.

In operation, after a starting warm-up period, operational cycling ofthe machine 10 is initiated. As an indexing step is completed bringing aset of core rods 50 into station A, the upset means (not shown) inturret 12 engages, and functions to move the head member 52 of each corerod 50 into the dotted line position shown in FIG. 3 thereby providingan aperture between body member 54 and head member 52 in the region ofshoulder 94 for fluid passage therethrough to/from orifice 90 viachamber 22 and passage 86. A fluid passageway is also provided throughsection or portion 70 of porous metal, through the intermediate section78, through the orifices 68, through the passage 86 and finally toorifice 90, or vice versa.

Also, as an indexing step is completed bringing a set of core rods 50into station A, the liner magazine and feeder assembly 28 is broughtinto operation so that a liner 26 is positioned from each core rod 50 ofthe set thereof at station A. Because of the reduced pressure in theindividual core rods 50, the liner 26 is brought into intimate face toface engagement with circumferential surface portions of respective corerods 50 and such liners 26 are held against the rods 50. At theinitiation of the next subsequent indexing step a check valve 104associated with conduit 20 is closed thereby maintaining subatmosphericpressures in conduit 20 and the individual core rods 50. This pressureis maintained throughout the entire next processing steps carried out atstation B upon the core rods 50 thus provided with liners 26.

Alternatively, instead of conduit 20 being placed in fluid communicationwith line 100 by means of low pressures associated with the suction sideof a pump 102 which operates continuously, the line 100 may beassociated with an accumulator vessel (not shown) which itself is heldat low pressures by an intermittently operating vacuum pump (not shown)whose operation is regulated by functionally associated pressureswitches and the like.

After the platen or turret 12 has been raised, indexed, and lowered withthe liner-covered, vacuumized core rods 50 being duly positioned inrespective injection molds 22 located at injection station B, hotplastic 30 is injected through injection nozzles 32 over the individualliners 26 between the contured cavity surfaces 36 of the injection molds22 to form a plurality of composite preforms 34. Typically, from about 4to 10 such preforms 34 may be simultaneously formed by a single set ofcore rods located in one side of platen 12. Generally, liners 26 aretemperature conditioned on their respective associated core rods 50 fora given time period prior to being exteriorally contacted by a layer ofhot injected thermoplastic resin at station B.

As will be understood from the preceding description herein,simultaneously with the injection operation occurring at station B, aliner loading operation is occurring at station A with other liners 26and another set of core rods 50 located along an adjacent side of turret12.

When turret 12 next undergoes it indexing sequence through anothersegment of machine cycle, the composite preforms 34 are transferred fromstation B to station C within the respective individual blow molds 24located in station C with the preforms 34 now being at an overallgenerally uniform temperature as desired for expansion (blowing). As theconduit 20 associated with the preform 34 equipped core rods 50 comesinto position at station C, it is placed in fluid communication by line26 with the discharge side of a fluid pressure pumpt 108 associated withline 106. A mechanical disabling means (not shown) disengages checkvalve 104 from its closed position, which changes pressure inside eachcore rod to atmospheric. Also, the upset means (not shown) in turret 12engages and functions to move again the head member 52 of each core rod50 into the dotted line position shown in FIG. 3, thereby providingagain the aperture between body member 54 and head member 52 in theregion of shoulder 94 for fluid passage therethrough here from orifice90 via chamber 22 and passage 86. The fluid passageway from orifice 90to porous metal section 70 is also open. A pressurized fluid (e.g.,compressed air or other gas) is thus permitted to flow through thepassageway 58 of each curved rod 50 and to exit between head member 52and body member 54 thereof thereby permitting the composite preforms 34to expand and move against the contured cavity surfaces 38 of eachassociated blow mold 24 and thereby form a plurality of containers 40,one on each core rod 50.

Thereafter, another segment of machine cycle is initiated, the platen 12is caused to raise index and then lower at the product removal station Dwhere the thus formed containers 40 are ejected by a mechanical means orthe like onto a conveyor 42 for subsequent processing operations (notshown), such as inspection, filling and packaging. It is to beunderstood that since each one of the four sides of the platen or turret12 is provided with a similar set of core rods 50, each core rod set isin a different operational step or segment of one complete machine cycleat any given time.

As herein above indicated, use of a porous metal core rod 50 of thepresent invention in a machine which is modified to permit theapplication of a vacuum within such core rods 50 during liner placementpermits such vacuum to be applied during linear placement on core rods,to be maintained during injection molding at preform 34 formation and tobe released before blowing. The vacuum holds the liners and prevents airpocket formation between a core rod 50 and a liner 26. By thisarrangement, liner creasing may be substantially completely eliminatedand product blown container defects are minimizable or completelyeliminated. Another advantage of a core rod 50 of this invention is thatit can make a fit between a liner and a core rod less critical than inthe prior art so far as the production of commercial quality blowncontainers is concerned. Also, liner dimensional tolerances in relationto a core rod size are not as critical when making multiwalledcontainers by injection blow molding when using a core rod 50 which canbe a significant cost saving feature from the standpoint of linerproduction.

Another feature is that the internal configuration of a core rod 50allows for the introduction and passage of a conditioning fluid, ifdesired, therethrough, such as hot air or other hot gaseous fluid duringa start-up of a machine 10 and its blow molding assembly. Also, aconditioning fluid can advantageously be fed through a core rod 50 afterproduct container removal therefrom, and before implacement thereon of aliner during a production cycle, if desired.

The uniform passage of a conditioning fluid, such as compressed air orthe like, through the porous face portion or section 74 of a core pinmember 72, in a core rod 50, is enhanced by the helically extendingthreadlike ribs thereof, including the flat crests on the intermediatesection 78 of the support member 72. Such a set of helically extendingthreads apparently enhances the even and uniform exiting of aconditioning fluid through the surface portions of section 74 owing tothe nature of porous metal. However, it will be understood that whilethe intermediate section 78 is here formed with a helically extendingthread section or portion the intermediate section 78 of a supportmember 62 may take other shapes, such as a star-shape support member inaxially alignment with a core pin member having flat axially andradially extending flat crests which contact an inner wall surface 70 ofa core pin member 60. The flat crests of threaded intermediate portion78 is presently preferred in order to provide a significant area ofcontact so as to enhance support for the core pin member 60 as well asto enhance conductive heat transfer from a tip section of core pinmember 60 to the interior portion of the core pin support member 62.

As hereinabove indicated, the support member 62 is preferably formed ofa heat conductive material, such as copper or the like, to provide forthe appropriate removal of heat, especially from the end portion 80 ofthe core pins 50, since the tip or end portion 80 thereof is normallysubjected to higher temperatures as a result of the positioning of thehot plastic injection nozzles 32, that is, generally opposite such endportion during the injection portion of a machine cycle. Consequently,in a preferred configuration, porous metal is not formed over the tip ofthe end portion 80. As hereinabove discussed, a core pin assembly 50 isassociated functionally with the platen 12 and may be provided withsuitable conduits for the passage of cooled or heated intermediate heattransfer medium therethrough to maintain desired temperature levels forcore rods (together with other potential conditioning requirements).

As will be appreciated by one skilled in the art, the base portion 72 ofthe core pin member 60 is formed of tool steel or stainless steel toprovide for a stronger contacting surface between the core pin headmember 52 and the body member 54 at the surface 94 thereby substantiallylengthening the useable life span of such a core rod 50 as distinguishedfrom the use of a core pin member 60 formed entirely of such porousmetal. It will be understood by those skilled in the art that theoptimized relative positioning of a blow slot in a core rod of thisinvention will vary depending on the plastic composition of thecomposite preforms involved in any given use situation as well as uponmachine operating conditions. For instance, for polystyrene, the blowslot can be positioned as generally illustrated in FIG. 3, whereas forpolyolefin, the blow slot can be generally located near a tip of a blowcore.

Additionally, while the present novel core rod assembly has beendisclosed with reference to a rotary injection blow molding apparatushaving a plurality of blow cores disposed along each side of the platenor turret thereof, it will be understood and appreciated that the corerod assembly may be used in any process and apparatus for injection blowmolding of articles (containers), such as a linear transfer injectionblow molding apparatus utilizing a single core rod, or the like.

It will be further appreciated that a core rod fabricated of a porousmetal may be used as the male member of a molding dye in a vacuumthermoforming process and apparatus to form the liner to be subsequentlyused in the hereinabove discussed process an apparatus for formingbarrier containers.

In operation, after a starting warm-up period, operational cycling ofthe machine 10 is initiated. As an indexing step is completed bringing aset of core rods 50 into station A, the upset means (not shown) inturret 12 engages, and functions to move the head member 52 of each corerod 50 into the dotted line position shown in FIG. 3 thereby providingan aperture between body member 54 and head member 52 in the region ofshoulder 94 for fluid passage therethrough to/from orifice 90 viachamber 22 and passage 86. A fluid passageway is also provided throughsection or portion 70 of porous metal, through the intermediate section78, through the orifices 68, through the passage 86 and finally toorifice 90, or vice versa.

Also, as an indexing step is completed bringing a set of core rods 50into station A, the liner magazine and feeder assembly 28 is broughtinto operation so that a liner 26 is positioned from each core rod 50 ofthe set thereof at station A. Because of the reduced pressure in theindividual core rods 50, the liner 26 is brought into intimate face toface engagement with circumferential surface portions of respective corerods 50 and such liners 26 are held against the rods 50. At theinitiation of the next subsequent indexing step a check valve 104associated with conduit 20 is closed thereby maintaining subatmosphericpressures in concuit 20 and the individual core rods 50. This pressureis maintained throughout the entire next processing steps carried out astation B upon the core rods 50 thus provided with liners 26.

Alternatively, instead of conduit 20 being placed in fluid communicationwith line 100 by means of low pressures associated with the suction sideof a pump 102 which operates continuously, the line 100 may beassociated with an accumulator vessel (not shown) which itself is heldat low pressures by an intermittently operating vacuum pump (not shown)whose operation is regulated by functionally associated pressureswitches and the like.

After the platen or turret 12 has been raised, indexed, and lowered withthe liner-covered, vacuumized core rods 50 being duly positioned inrespective injection molds 22 located at injection station B, hotplastic 30 is injected through injection nozzles 32 over the individualliners 26 between the contured cavity surfaces 36 of the injection molds22 to form a plurality of composite preforms 34. Typically, from about 4to 10 such preforms 34 may be simultaneously formed by a single set ofcore rods located in one side of platen 12. Generally, liners 26 aretemperature conditioned on their respective associated core rods 50 fora given time period prior to being exteriorally contacted by a layer ofhot injected thermoplastic resin at station B.

As will be understood from the proceding description herein,simultaneously with the injection operation occurring at station B, aliner loading operation is occurring at station A with other liners 26and another set of core rods 50 located along an adjacent side of turret12.

When turret 12 next undergoes its indexing sequence through anothersegment of machine cycle, the composite preforms 34 are transferred fromstation B to station C within the respective individual blow molds 24located in station C with the preforms 34 now being at an overallgenerally uniform temperature as desired for expansion (blowing). As theconduit 20 associated with the preform 34 equipped core rods 50 comesinto position at station C, it is placed in fluid communication by line26 with the discharge side of a fluid pressure pumpt 108 associated withline 106. A mechanical disabling means (not shown) disengages checkvalve 104 from its closed position, which changes pressure inside eachcore rod to atmospheric. Also, the upset means (not shown) in turret 12engages and functions to move again the head member 52 of each core rod50 into the dotted line position shown in FIG. 3, thereby providingagain the aperture between body member 54 and head member 52 in theregion of shoulder 94 for fluid passage therethrough here from orifice90 via chamber 22 and passage 86. The fluid passageway from orifice 90to porous metal section 70 is also open. A pressurized fluid (e.g.,compressed air or other gas) is thus permitted to flow through thepassageway 58 of each curved rod 50 and to exit between head member 52any body member 54 thereof thereby permitting the composite preforms 34to expand and move against the contured cavity surfaces 38 of eachassociated blow mold 24 and thereby form a plurality of containers 40,one on each core rod 50.

Thereafter, another segment of machine cycle is initiated, the platen 12is caused to raise index and then lower at the product removal station Dwhere the thus formed containers 40 are ejected by a mechanical means orthe like onto a conveyor 42 for subsequent processing operations (notshown), such as inspection, filling and packaging. It is to beunderstood that since each one of the four sides of the platen or turret12 is provided with a similar set of core rods 50, each core rod set isin a different operational step or segment of one complete machine cycleat any given time.

As herein above indicated, use of a porous metal core rod 50 of thepresent invention in a machine which is modified to permit theapplication of a vacuum within such core rods 50 during liner placementpermits such vacuum to be applied during liner placement on core rods,to be maintained during injection molding at preform 34 formation and tobe released before blowing. The vacuum holds the liners and prevents airpocket formation between a core rod 50 and a liner 26. By thisarrangement, liner creasing may be substantially completely eliminatedand product blown container defects are minimizable or completelyeliminated. Another advantage of a core rod 50 of this invention is thatit can make a fit between a liner and a core rod less critical than inthe prior art so far as the production of commercial quality blowncontainers is concerned. Also, liner dimensional tolerances in relationto a core rod size are not as critical when making multiwalledcontainers by injection blow molding when using a core rod 50 which canbe a significant cost saving feature from the standpoint of linerproduction.

Another feature is that the internal configuration of a core rod 50allows for the introduction and passage of a conditioning fluid, ifdesired, therethrough, such as hot air or other hot gaseous fluid duringa start-up of a machine 10 and its blow molding assembly. Also, aconditioning fluid can advantageously be fed through a core rod 50 afterproduct container removal therefrom, and before implacement thereon of aliner during a production cycle, if desired.

The uniform passage of a conditioning fluid, such as compressed air orthe like, through the porous face portion or section 74 of a core pinmember 72, in a core rod 50, is enhanced by the helically extendingthreadlike ribs thereof, including the flat crests of the intermediatesection 78 of the support member 72. Such a set of helically extendingthreads apparently enhances the even and uniform exiting of aconditioning fluid through the surface portions of section 74 owing tothe nature of porous metal. However, it will be understood that whilethe intermediate section 78 is here formed with a helically extendingthread section or portion the intermediate section 78 of a supportmember 62 may take other shapes, such as a star-shape support member inaxially alignment with a core pin member having flat axially andradially extending flat crests which contact an inner wall surface 70 ofa core pin member 60. The flat crests of threaded intermediate portion78 is presently preferred in order to provide a significant area ofcontact so as to enhance support for the core pin member 60 as well asto enhance conductive heat transfer from a tip section of core pinmember 60 to the interior portion of the core pin support member 62.

As hereinabove indicated, the support member 62 is preferably formed ofa heat conductive material, such as copper or the like, to provide forthe appropriate removal of heat, especially from the end portion 80 ofthe core pins 50, since the tip or end portion 80 thereof is normallysubjected to higher temperatures as a result of the positioning of thehot plastic injection nozzles 32, that is, generally opposite such endportion during the injection portion of a machine cycle. Consequently,in a preferred configuration, porous metal is not formed over the tip ofthe end portion 80. As hereinabove discussed, a core pin assembly 50 isassociated functionally with the platen 12 and may be provided withsuitable conduits for the passage of cooled or heated intermediate heattransfer medium therethrough to maintain desired temperature levels forcore rods (together with other potential conditioning requirements).

As will be appreciated by one skilled in the art, the base portion 72 ofthe core pin member 60 is formed of tool steel or stainless steel toprovide for a stronger contacting surface between the core pin headmember 52 and the body member 54 at the surface 94 thereby substantiallylengthening the useable life span of such a core rod 50 as distinguishedfrom the use of a core pin member 60 formed entirely of such porousmetal. It will be understood by those skilled in the art that theoptimized relative positioning of a blow slot in a core rod of thisinvention will vary depending on the plastic composition of thecomposite preforms involved in any given use situation as well as uponmachine operating conditions. For instance, for polystyrene, the blowslot can be positioned as generally illustrated in FIG. 3, whereas forpolyolefin, the blow slot can be generally located near a tip of a blowcore.

Additionally, while the present novel core rod assembly has beendisclosed with reference to a rotary injection blow molding apparatushaving a plurality of blow cores disposed along each side of the platenor turret thereof, it will be understood and appreciated that the corerod assembly may be used in any process and apparatus for injection blowmolding of articles (containers), such as a linear transfer injectionblow molding apparatus utilizing a single core rod, or the like.

It will be further appreciated that a core rod fabricated of a porousmetal may be used as the male member of a molding dye in a vacuumthermoforming process and apparatus to form the liner to be subsequentlyused in the hereinabove discussed process and apparatus for formingbarrier containers (eg. multiwalled containers having at least onebarrier layer of thermoplastic resin and at least one support layer ofthermoplastic resin).

Referring to FIG. 4, there is seen another embodiment of a core rodassembly, generally designated as 110, comprising a body or supportmember 112 and a core rod head member 114.

The support 112 is generally goblet shaped, being provided with an uppergenerally cylindrically sided cup section 111 and on integral lower stemsection 113 which is coaxial with such cup section 111. A channel orbase 152 axially entends through stem 113. Section 111 has a mouth 115which is coaxial with the inside walls of section 111.

The open end of stem 113 is counterboard by a first channel 121 and by asecond channel 123 which is deeper than first channel 121 and of smallerdiameter. Both channels 121 and 123 are coaxial with channel 152.

The core rod head 114 is generally cross sectionally circular externallyand incorporates a disc-shaped base 118 and an elongated hollow core120. The main section 122 of core member 120 is comprised of a singlepiece of material, such as hardened cold rolled steel or the like, andis abuttingly engaged at the front end thereof with a sleeve section 124of a porous metal material which has a multiplicity of discretepassageways formed therein during fabrication thereof such as fromsintered stainless steel pellets, or the like, as more particularlydescribed hereinafter.

The forward inner wall surface portions 128 of main section 122 areformed with a taper so that the internal diameter of hollow core member120 in this region declines with increasing distance from base 118.Behind portion 128 is a cylindrical surface 132 which terminates in ashoulder 130 that is adjacent portion 128. Behind surface 132 is anothercylindrical surface 134 having a larger diameter than that of surface132; surface 136 terminates in a shoulder 134 adjacent surface 132.Surface 136 may be slightly tapered, if desired. Behind surface 136 is arear cylindrical surface 140 which has a larger diameter than surface136. Surface 140 terminates in a shoulder 138 adjacent surface 136.

The base 118 has circumferential outer walls which are press fitted intoand along surface 140 against shoulder 138 across the rear opening 142of main section 122. The base 118 is also provided with an axiallyextending threaded tap 147 and a plurality of bores or orifices 148which are in radially spaced relationship to tap 147 and incircumferentially spaced relationship to each other. An actuator rod 144which is threaded at its opposite ends is engaged at one end thereofwith tap 147.

The rear portion of main section 122 has an outside diameter which isless than the inside diameter of cup section 111 so that such isreceivable therewithin coaxially until a circumferential shoulder 145 onthe outside of section 122 engages an inner ledge 164 on the rim of themouth 115 of cup 111.

Rod 144 extends loosely through channel or bore 152, bore 121 and bore123, and is threadably connected to star nut 156 and locking nut 158which are in channel 121.

Compression spring 160 is positioned about rod 144 in channel 123between star nut 156 and shoulder 162 at the end of bore 152. Spring 160biases the rod 144 and core 120 to a seated engagement with mouth 115where annular beveled ledge 164 on body 112 nests against annularbeveled ledge 166 on base 122, to thereby normally form an annular blowslot 119 defined between body 112 and head 114. During portions of onecycle of injection blow molding, as herein elsewhere explained, amachine in which the core rod assembly 110 is employed applies pressureupon nut 158 to open blow slot 119 against the bias of spring 160. Theapplied pressure pushes actuator rod 144 forward against the biasingforce of spring 160 and causes ledge or seat 164 to move away from ledgeor seat 166, thereby providing a space or blow slot 119 therebetween.

Insert 150 has a heat transfer function; it abutts against front side ofdisc 118 and coaxially extends through core 120. It has, successively, afirst cylindrical 184, a second cylindrical section 168 of greaterdaimeter than section 184, a third cylindrical section 170 of greaterdiameter than section 168, a fourth still greater diameter cylindricalsection 172 with a rim 174 which appears around its outer rear surface,and a fifth or rear reduced diameter cylindrical section 176. Whenmounted within core 120, the front surface of 184 of insert 150 isconterminous with the frontal surface of the tip 126 with the rim 174 ofinsert 150 abutting against shoulder 134 and the front ede of section170 abutting against porous ring 124. When so mounted, the outer surfaceof section 168 of insert 150 contacts the respective inner surface oftip 126 and porous ring 124. In addition, the front portion of the outerperipheral surface of section 170 of insert 150 is in contact with theinner surface 128 of core 122. The contacting surface of ring 126,insert 124, and main section 122 with insert 150 provides for thedissipation of heat from the front of core pin 120 to its rear portions.Cylindrical portion 168 of insert 150 extends through porous sleeve 124and a retaining collar 126 is mounted circumferentially aboutcylindrical section 184. Collar 126 is secured to insert 150 by aretaining pin 179 extended into hole 180 diametrically through collar126 and section 184. Porous sleeve 124 is thus secured in place oninsert 150 between collar 126 and main section 122.

Insert 150 is generally formed of a heat conductive material, such ascopper, a copper alloy, or the like, to provide for the removal of heat,especially from the front end portion of core 120, since the collar 126thereof is normally subjected to higher temperatures as a result of thepositioning of the hot plastic injection. nozzles, that is generallyopposite such end portion during the inject phase of a machine 10 cycle(see, for example nozzle 32 in FIG. 1). Consequently, in a preferredcore rod assembly configuration, porous metal is not used in the collarregion 126 since a solid metal region here more readily allows transferof heat therefrom to an adjacent insert 150 and thus aids in theprevention of localized overheating of the forward portion of a core rodof this invention.

For occurring during a blow molding cycle, air passageway means areprovided between rear opening 182, end bore 152 in core 112 and poroussleeve 124. Tracing this passageway which is used primarily inevacuation from rear opening 182, air can pass around star nut 156,through bore 123 and 152 in support member 112, orifices 148 in base118, and into the interior of insert 150 by means of hole 186 in insert150. The air is allowed to pass through a major length of insert 150 bymeans of bore 188, axially positioned within insert 150 and terminatedin intermediate front section 168. From bore 188, air passage continuesin an outward direction through hole 190 in insert 150 thiscommunicating bore 118 with an annular groove 192 in the outerperipheral surface of section 168 of insert 150. Communicating withannular groove 192 are a plurality of air passageway channels 194extending axially along the length of the outer surface of section 168adjacent porous sleeve 124. Communication is thereby provided betweenchannels 194 and porous sleeve 124.

In addition, for pressurization during a blowing operation, a passagewayis provided from rear opening 182 to blow slot 119 by means of bores 123and 152, chamber 116 and flats 185 axially extending along a surfaceportion of core 122. Annular recess 187 is provided around core rod base122 to aid the flow from flats 185 to blow slot 119 when blow slot 119is in the open position. A small amount of air also exits from poroussleeve 124 during blowing; however, the major portion of the blowingfunction occurs through blow slot 119.

The outer surface of main section 122 here has an optical taperedportion 196 for guiding the open end 199 of a liner 201 (shown inphantom in FIG. 4) to a position adjacent cylindrical surface 198 ofcore body member 112 as liner 201 is inserted over core rod head 114.The edge of the open end of liner 201 abutts annular shoulder 200 ofbody 112 at the termination of the insertion movement.

To prevent only substantial shrinkage of liner 201 as the liner becomesheated from its contact with core 120, an annular ridge 202 on surface198 is provided. As the liner 201 becomes hot, a portion of liner 201conforms around ridge 202 to secure the liner 201 adjacent its open end199 to the support 112.

A polytetrafluoroethylene layer 125 is coated onto, or otherwise appliedto core 120 on the surface areas to be covered by a liner such as liners201. As indicated in FIG. 4, the layer 125 extends from the back edge214 of tapered portion 196 up to and including front edge 216 of corerod head 114.

It is preferred that the ledge 164 on support 112 and ledge 166 on core120 be not coated with layer 125 to avoid the possibility of adverselyaffecting the sealing of blow slot 119 as ledges 164 and 166 engage eachother.

It is also preferred that the surface 198 on support 112 be not becoated with layer 125 becuase if this area were so coated, then thereduced coefficient of friction might tend to increase shrinkage orslippage of a liner 201 and counteract the gripping function provided byridge 202 as previously discussed. Also, since the portion of a liner201 contacting surface 198 is not blown, and since such portion isgenerally not as hot as the forward area thereof, there is reducedtendency for the liner to exhibit undesirable sticking in the adjacentsurfaces 198.

In the application of a layer 125 to cores 120 having porous section124, any conventional appropriate coating procedure may be used.However, it is now preferred to spray a liquid polytetrafluoroethylenesystem on a core 120 to a thickness of about 0.0005 inch, including afront face portion section 184 of insert 150 if the front face ofsection 184 is to contact a liner 201 as in in FIGS. 1 and 2, and thenis baked until such coating becomes a solid.

The porous material of porous section 124 is formable by any convenientconventional techniques and preferably is now comprised of sinteredmetal particles, such as 316L stainless steel or the like. Preferablythe porous metal section 124 has a filtration rating of 1/2 to 5microns.

Porous metal pore size ratings of from about 0.5 to 5 microns arepreferred. Pore sizes above about 5 microns may cause markings to bepicked up by the liners or parisons which markings may thereafter appearupon a finished container which may be undesirable in commercial qualitycontainers.

A 0.0005 inch thick single layer of coating 125 is preferably applied toa core rod 120 over the porous section 124 in addition to the othersurface areas indicated. Quite surprisingly, it is found that such acoating 125 does not plug pores of porous section 124 so as to preventeffective passage of air therethrough.

Polytetrafluoroethylene is available commercially as "Teflon" (atrademark of the DuPont Company). "Teflon-S" is the preferred coatingand can be applied as a liquid in a single coating to a clean, untreatedmetal.

Layer 125 reduces sticking problems, tends to act as an insulator toprevent the overheating of a liner 201 without the use of coolingdevices, and aids in the evacuation of air between a core rod and aliner.

The support 112 of core rod assembly 110 is circumferentially grooved ina location 218 adjacent the open end of stem 113. The groove 218 permitsthe entire core rod assembly 110 to be conventionally mounted in aretaining strip 219 forming part of the assembly of the turret 220, suchturret 220 being similar to 12 in structure and function and thereforeadapted for use in the machine 10, as hereinafter described. (See FIGS.4 and 5, for example.)

The retaining strip 219 is bolted to a retaining bar 221 (bolts notshown). The retaining bar 221 is in turn bolted to the body 222 ofturret assembly 220. The bar 221 is provided with as many mounting holds223 as is desired for the number of core rod assemblies 110 to be usedwith a given turret assembly 220 in any given circumstance. Suitable Oring sealing means 223 or the like are provided to provide a gas typejoint between the stem, section 113, and the bar, 221. A channel 224 isprovided in the body 222 which interconnects with each of the openings,182. Located in the channel 224 along each side of the body 222 is anactuating bar 225 which is mounted for reciprocal transverse movementstowards and away from the retaining bar 221. The bar is thus adapted tomake contact with the head portion of each nut 158 which thereby permitsthe bar 225 to effectuate opening movements of the blow slot 119 of eachcore rod assembly 110. The actuating bar 225 is itself moved against thenuts 158 by means of a fluid cylinder assembly 226 whose piston isslotted to receive the bar 225. The piston 227 is also adapted toreceive a pin 228 so that the combination of pin and slot controlspositioning of the bar 225 (that is, the bar is upheld and preventedfrom shifting laterally thereby). The cylinder 226 is itself seated inthe body 222 of turret 220 by any convenient means (such as screws orthe like). A system of pressurizable passageways 228 is provided in thebody 222 for supplying to piston 226 with pressurized fluid (such ascompressed air or the like). When pressure is applied to a cylinderassembly 226 through the system of channels 228 the piston 227 isactuated thereby moving the bar 225 so as to open the blow slots 119 ofthe individual core rod assemblies 110. The bar 225 moves against thebiasing force exerted by 160 in each core rod assembly 110. Whenpressure in the cylinder's assembly 226 is cut off, the springs 160function to close each blow slot 119 and to retract the piston 227 intocylinder assembly 226. Each set of core road assemblies 110 thus mountedin each side 230 of the turret assembly 220 is similarly provided withmeans for controllably opening the respective blow slots 119 of the corerod assemblies 110 associated therewith.

When a turret assembly 220 is operatively associated with a machine 10in the manner of turret 12, the control actuation of the bar 225 isaccomplished as follows at a station, such as station A in FIG. 1: Aport 231 formed in the lower face of body 222 communicates with thepassageway system 228 centrally. When, for example, turret assembly 20has been duly indexed to station A, the port 231 comes into registrationwith a pressure port 232 of a pressurized fluid supply system generallydesignated by the numeral 233. In order to make a fluid tight sealbetween the port 231 and the pressurizable fluid system 233, a so-calledmushroom head is employed in the embodyment shown, such mushroom headsub-assembly being designated in its entirety by the numeral 234. Herethe mushroom head has a face portion 235 which is associated with O-ringsealing ring 236. When the turret 220 is duly in position at station A,the O-ring seal 236 accomplishes a gas type seal with body 222 and themushroom head 234 is depressed against the yielding bias of acompression 237 associated with the fluid supply system 233. The fluidsupply system 233 can be of conventional construction and, as such, doesnot constitute a portion of the present invention. The pressurizablefluid supply system 233 in the region of the turret assembly 220 atstation A is housed in a pressure block 239. The pressurizable fluidsupply system 233 is actuated so as to deliver a pressurized fluid tothe system of passageways 228 by the machine 10 control system (ashereinafter discussed).

In order to control the pressure within the core rod assemblies 110 atstation A when the blow slots 119 of the individual core rod assemblies110 are thus opened by actuating bar 225, the following arrangement isprovided: A vacuum system at station A is provided which providessub-atmospheric pressures within an individual core rod assembly 110 notonly at the blow slot 119 thereof, but also in the region of poroussections 124 thereof. The channel 224 is in fluid communication with acentral passageway 239 in body 222. The passageway 239 is provided witha check valve assembly 240 which is positioned in body 222 so as to beopenable and closeable by an actuating rod located beneath the body 222but aligned with the check valve assembly 240 when the turret assemblyis in a properly indexed location, such as, in the illustrative example,position A. Specifically, a push rod 241 opens the check valve assembly240 by contact with a poppit valve 242. Thus, when the turret assembly220 has completed an index and is located at station A in registrationwith lock 238, a second mushroom head sub-assembly 243 comes intoregistration with that region of body 222 circumferentially locatedaround the check valve assembly 240 and an O ring seal 244 makes asealing engagement with body 222. The operation of the mushroom head 243is similar to that of mushroom head 234 and such operations areconventional to those skilled in this art. A conduit 245 interconnectswith the region of mushroom head 243 so that when the push rod 241 hasopened poppit valve 242 sub-atmospheric air pressures may be exertedpast the valve assembly 240 in the interior of each core rod assembly110, so that all of the core rod assemblies along one side of the turretassembly 220 are vacuumized in the region of station A. Any convenientmeans for supplying a sub-atmospheric vacuumized gas pressure to conduit245 may be employed, as those skilled in the art will appreciate. It isnoted that, referring to FIG. 2, check valve 104 is comparable infunction and operation to the check valve assembly 104.

With the core rod assemblies 110 at station A thus vacuumized with therespective blow slots 119 open, the liners 201 are individually loadedover each core rod assembly 110. When the liner loading operation atstation A is completed, the machine 10 is subjected to an indexingoperation under which the turret assembly 220 operates similarly toturret 12. Thus, the turret assembly 220 is raised, indexed and lowered.As soon as the turret assembly 220 is raised, the check valve assembly240 is closed thereby holding sub-atmospheric pressures in centralpassageway 239 and consequently in the interior of each core rodassembly 110. Because of the close-fitting nature of liner contact 201with each core rod assembly 110, a sealing engagement exists therebetween so that air pressure is not appreciably lost between each liner201 and its associated core rod assembly 110. Continued movement of theturret assembly 220 upward then breaks the sealing connection betweenthe body 222 and the mushroom head 243.

Concurrently, as the turret assembly 220 is being raised, fluid pressureis cut off in pressurizable fluid supply system 233 (by means of valvemeans not shown but see description below) and as the turret assemblycontinues to raise disengagement occurs between the mushroom head 234and the body 222. Thus pressure is lost in cylinder assembly 226 and theblow slots 119 of all associated core rod assemblies 110 are closed.

When these liner-equipped vacuumized core rod assemblies 110 becomeindexed and located at station B, as is above-described and as belowdescribed, at station B the normal and usual injection operation takesplace wherein a pre-form assembly utilizing the liners 201 takes place.Observe that during the operations at station B, vacuum is continuouslymaintained within the individual core rods 110 located thereat and alsoobserve that the blow slots 119 of all core rods remain closed, in thepresent preferred mode of operating this invention. However, optionally,during the injection operation occuring at station B one could havemeans similar to that above described in relation to station A forfortifying the vacuum pressures within the individual core rods 110. Themaintenance of a relatively low vacuum pressure on the core rods 110 maybe advantageous when using certain types of plastic which have viscositycharacteristics and heat-softening characteristics as such that closecontact between core rod assemblies and liners should be maintained foroptimum product container quality.

After the injection operation at station B is duly completed, a cycle ofindexing is undertaken for turret assembly 220 and the assembly 220 isthus rotated so as to bring the core pins which were previously atstation B around so that they are now resident at station C. During thisrotation, a vacuum is still maintained in the individual core rodassemblies 110. However, as the turret assembly 220 descends, the corerod assemblies at station C are subjected to pressurization in thefollowing manner: an arrangement similar to that shown in FIG. 6 isimplaced at station C. Again, pressure in system 228 is achieved so thatthe blow slots 119 of all core rod assemblies are open. However, inaddition, when the check valve assembly 240 is opened by push rodassembly 241 at station C, pressurized fluid is admitted through channel245. Observe that as soon as the poppet valve 242 is displaced, thevacuum pressure within the individual core rod assemblies is lost. Theair pressure in conduit 245 is adjusted so as to achieve a predetermineddesired gas pressure or fluid pressure at blow slots 119, this pressurebeing sufficient to expand the preform system on the core rod assemblies110 into engagement with the adjacent wall portions of the blow holds atstation C. Because of the pressure/time considerations involved, theblowing accomplished at station C is achieved largely with fluidpressure developed through the blow slots 119 rather than through thepores associated with the sleeve 124. Typically, the rate of gas flowthrough a sleeve 124 is less than that which is sufficient to build upthe desired gas pressure level between the core rod 110 and a preformthereon during the cycle time of a blowing operation at station C.

Thereafter, after the blowing operation at station C is completed, gaspressure in conduit 245 is cut off (that is vented) so as to allow thesuper-atmospheric fluid pressure with individual containers 40 to ventto atmosphere.

Next another cycle of machine indexing is undertaken and the turretassembly is raised, rotated and permitted to descend so that thefinished container may be ejected at station D routinely. In normaloperation, in accordance with the practice of this invention, nopressurization or vacuumization of core rod assemblies 110 occurs.However, under certain operational conditions, such as at the time ofmachine 10 start-up, it has been found advantageous to be able topressurize containers at station D for removing same from the core rodassemblies 110 since at station D during a startup mode the temperatureof the core rod assemblies 110 may not be sufficiently high to achieve asimple and convenient removal of form containers therefrom.

Referring to FIGS. 7 and 8, embodiments of alternative core rodassemblies of this invention are seen illustrated. In the case of FIG.7, components thereof which are similar to the components of core rodassemblies 110, are similarly numbered but with the addition of primemarks thereto. Similarly, in the case of the embodiment shown in FIG. 8,the components which are similar to the components of core rod assembly110 are similarly numbered but with the addition of double prime marksthereto.

Embodiment 110 prime employs a core rod head 114 prime whereinsubstantially the entire circumferential body portions are comprised ofa porous metal except for the retaining collar 126 prime. The corehowever instead of being like insert 150 provides a fluid communicationalong substantially the entire tapered surface region of head 114 primeby means of a spirally threaded section 246.

The embodiment shown in FIG. 8 employs a porous metal sleeve 147inserted circumferentially about the body of a core rod head 114 doubleprime which body 114 double prime is comprised of tooled steel or thelike. In this embodiment, the push rod 144 double prime extends axiallythrough the core rod head 114 double prime and when actuated a blow slow249 opens at the tip region of head 114 double prime. Immediately afterthe blow slot 249 opens a secondary blow slot 119 double prime opensbecause an actuating ring 250 carried by the rod 114 double prime buttsthe back of the head 114 double prime and moves the same reciprocallyand axially. A gas passageway circumferentially around rod 144 doubleprime permits delivery of pressurizing fluid to channels 253 whichradially extend outwardly from channel 251 so as to pressurize orvacuumize the section 247, as desired.

The type of problems occurring without the porous metal insert providedby the core rod construction of the present invention are illustrated inFIGS. 9 and 10. Thus, in FIG. 9, the type of blister which can occur inmaking a multi-walled container by injection blow molding isillustrated. Here, a liner 254 mounted over a core rod assembly 255experiences entrapment of a pocket of air 256 in the region of the liner254 over the pocket 256 irregular heating can occur to such an extentthat a form of overlapping of liner upon itself can occur, the effectsometimes being called creasing. For example, hot plastic striking ablister or bubble 256 causes the liner in such region to fold over.Alternatively, as in the case of small gas blisters 256 the injectedplastic may form only a thin layer over a liner in such region; theappearance of such a locally thinned injected plastic overlayment isillustrated in FIG. 10 at location 257.

Referring to FIG. 11 there is seen illustrated one diagrammaticrepresentation of a functional control arrangement of the general typeemployed for the operation of a blow molding machine 10 within which thecore rod assembly of the present invention is useable. In operation, acontrol unit 260 is arranged to energize a celanoid valve 261 of a gasvalve 263 thereby to pressurize the cylinder 263 which is functionallyattached to a press fram 264. The press frame 264 carries thereon anupper half of an injection cavity block 266 as well as an upper half ofa blow mold block 267. The upper locks 266 and 267 are moved downwardlyby the lowering action of the cylinder 263 into engagement with lowerhalf portions 268 and 269 of respective complementary injection and blowmold blocks. A second air cylinder 271 supported from the frame 264supports a turret frame 272. Frame 272 is adapted for indexing rotarymotion relative to the framed 264 (not detailed in FIG. 11). The aircylinder 271 may be cross connected by lines 273 and 274 to pressurelines 275 and 276, respectively, in which opposite motions are producedin the cylinders. Thus, as the cylinder 263 moves downward with theframe 264, and the units carried thereon, the cylinder 271 moves upward(relative to the frame 264) with the turret 272. Thus, when the cylinder263 is fully extended and blocks 266 and 268 are in a suitable buttingrelationship, as well as the blocks 267 and 269 the cylinder 271 isfully retracted to place the turret frame 272 at a desired or requiredposition relative to the respective blocks 266, 268, 267 and 269, or, inother words, in a required low mold position. Conversely, when the frame264 is raised, the turret 272 is lowered with respect to its positionrelative to the frame 264 from which it depends. A 90° indexing drive277 provides the means for rotating the turret 272 so as to bring agroup of preforms sequentially into the several machine functionalstations involved.

With the descent of the turret 272 to the position shown in, forexample, FIG. 11, mechanical connections are completed with the mushroomhead fluid connection previously described. Now, at a liner feederstation A connection is accomplished with the pressure head 234 and thevacuum head 227 in preparation for loading liners on the respective corerods. A sensor means 278 (such as a limit switch or the like) isprovided to indicate that the turret 272 is in position and beginning atimed sequence, including providing an operating signal to energize asolenoid 279 of a valve 280 to deliver air pressure to the pressure head234 to open the respective core rod assembly 110 (or the like) aspreviously described. After the core rods 110 open, a vacuum isdeveloped there within which facilitates the loading of liners onto theindividual rods 110. After a predetermined time period, as set by atimer 281 in the control unit 260 the solenoid 261 actuates the valve262 to pressurize the lines 275 and 273 to retract the cylinder 263while extending the cylinder 271. Thus, the liners on the respectivecore rods of the turret 11 may clear both the blocks 266 and 268 whilebeing rotated to the next or injection molding station B position. Upona raising of the turret 272, the mushroom head device 227 allows thecheck valve 240 to close and to hold a vacuum in the core rod systemwhereby the liners are not allowed to deform due to shrinkage.

Just prior to raising, the control unit 260 actuates the solenoid 279 tocause the valve 280 to discontinue pressure communication with themushroom head 234. Now the machine 10 is ready for sequencing. Thesensor 282 then indicates that the turret 272 and frame 264 have beenraised to a pre-determined indexing position. The control unit 260thereupon energizes the indexing drive 277 to move the liner loaded corerod assemblies 110 to station B. An indexing switch 283 is here employedto bring the turret 272 to a predetermined stop position (e.g. 90° withrespect to the starting position). At position B, control unit 260energizes the solenoid 261 which operates the air valve 262 to begin theoperation of the cylinder 263 thereby lowering the turret 272 and theframe 264 to their stationery respective configurations. The same stepoperating sequence is employed here as was employed earlier in thepreceding description above provided in relation to station A. Observethat all machine operating steps are occurring at each of the fourstations simultaneously with respect to the core rod assembly or setslocated at each operating station in a given sequence or mode.

After the frame and turret have dropped down in station B to the generalconfiguration illustrated in FIG. 11 (as detected by sensor 278). Assoon as contact is made with sensor 278 (as by turret 272) the controlunit 260 initiates a measured time delay period wherein the drivemechanism for the injection apparatus 284 is started after the timedelay period is over. Thereafter the injection apparatus 284 is cycledthrough its preset routine governed by the timer 286 governed by thecontrol unit 260. The details of operation of the injection apparatus284 are well known to those skilled in the art and do not constitute apart of the present invention; hence, such details are not providedherein.

After the end of the injection operation, the control unit 260 operatingthrough its timer mechanism signals the solenoid 261 which actuates thevalve 262 and causes the cylinder 263 to raise the frame 264 and theturret 272. Then, after raising is completed, machine turret indexingoccurs as previously described with the actuation of the drive 277. Whenindexing is completed, the control unit 260 operating through celenoid261 actuates cylinder 263 to lower frame 264 and turret 272. At thispoint, which involves station C in this description, the preform on thecore rods are blown after being duly placed in the blow mold cavities.In the blowing sequence, the control unit 260 works through a time delayafter which a timer 287 is actuated to energize solenoid 288 which, inturn, opens a valve 289 thus admitting air pressure to mushroom head227. Also, the action taken is similar to that experienced above inrelation to solenoid 279 and valve 280 except that here solenoid 290 andvalve 291 are operated, thereby to open the blow slots 119 of the corerod assemblies 110 operatively in position at station C. After asuitable length of time, the valve 289 is deactuated by solenoid 288thereby venting air from the interior of the core rod assemblies 110 aswell as from the interior of the blown containers. Then the machine issequenced as described above, (involving raising, indexing and loweringturret 272) so that the blown bottles become positioned at station D. Atstation D a stripper bar 292 comes into operation and, in its position,pulls the blown containers away from engagement at their neck portionsfrom the respective cylindrical core rod assemblies 110. To achieve thiseffect, solenoid 293 is actuated by control unit 260 thereby to operatevalve 294 which, in turn actuates cylinder 295 thereby causing thestripper bar 292 to translate and achieve its working function asdescribed. At the end of its stroke cylinder 295 has brought a stripperbar 292 into engagement with the sensor 296 whereupon solenoid 293 isdeactuated and the cylinder 295 returns the stripper bar 292 to itsstart position.

Finally, the machine is sequenced once again, in the manner earlierdescribed, to bring the core rod set back into a liner loaderconfiguration so as to complete one full operation of machine cycling.

The porosity rating of a porous metal insert used in a core rod asherein described can be measured by any convenient procedure. Onepresently used procedure involves the use of a curve chart whereinpressure (in pounds per square inch) is plotted against porosity inmicrons. To use this chart, a porous metal sleeve or other porous metalshaped component of a core rod of this description is immersedcompletely in an alcohol and then is clamped in a holder so thatcompressed air can be forced through such component, the pressure beingapplied in a direction and manner corresponding to that as usedrespectively in an actual core rod. For example, when such component issleeve-shaped, the air is forced radially through from the inside outwith the opposed side wall portions thereof being clamped in a gas tightarrangement. Gas pressure against the component (as indicated) isincreased until bubbles start to appear on a side of such componentgenerally opposed to that against which such pressure is applied atwhich point the pressure is noted, compared to the chart, and theporosity value in microns read off.

The process step sequence utilized in the invention is shown in FIG. 12.

Although the teachings of our invention have herein been discussed withreference to certain specific disclosures and embodiments, it is to beunderstood that these are by way of illustration only and that othersmay wish to utilize our invention in different designs or applications.

I claim:
 1. A core rod assembly for blow molding a hollow thermoplasticarticle from a preform on said core rod assembly which comprises:a bodymember including a chamber and provided with conduit means; and a headmember slidably mounted within and extendible relative to said chamber,thereby forming a blow slot between said body member and said headmember, said head member including a base member, and a core pin membermounted to said base member, said core pin member and said body memberhaving respective adjacent outer surfaces for receiving said preformthereover, said head member having an internal fluid passageway, saidcore pin member being formed in part of sintered porous metal having aporosity of from about 1/2 to 5 microns extending on a portion of saidouter surfaces thereof, said internal fluid passageway and said conduitmeans being in fluid communication with said porous metal therebypermitting passage of a fluid through such porous metal portion andpermitting the passage of a fluid through said blow slot when said blowslot is open.
 2. The core rod assembly as defined in claim 1 whereinsaid body member and said head member are generally coaxial and saidbase member includes a core pin support member coaxially extendingwithin said core pin member.
 3. The core rod assembly as defined inclaim 2 wherein said base member is spring biased with respect to saidbody member to maintain said blow slot in a normally closed position. 4.The core rod assembly as defined in claim 3 wherein said core pinsupport member is formed in part of a material having a high heattransfer coefficient.
 5. The core rod assembly as defined in claim 4wherein said core pin support member is formed in part with an outersurface of a helical configuration which contacts the inner surface ofsaid core pin member.
 6. The core rod assembly as defined in claim 5wherein the forward end of said core pin support member is coterminouswith the forward end of said core pin member.
 7. The core rod assemblyof claim 1 wherein said outer surfaces of said core pin member arecoated with a layer of polytetrafluoroethylene up to a thickness ofabout 0.0005 inch.
 8. A core rod assembly for injection blow moldingmultilayered thermoplastic articles comprising:(A) a generallycup-shaped body member having a mouth, side walls which are internallygenerally cylindrical, an integral bottom wall, and an integral stemmember extending rearwardly from said bottom wall relative to saidmouth, said stem member having a longitudinal continuous body channelmeans defined therein extending through said bottom wall and said stemmember, (B) an elongated, cross sectionally externally generallycircular head member having a front section and a rear section, saidhead member being generally coaxial with said body member,said rearsection being telescopically slidably reciprocable in said body memberthrough said mouth thereof, said front section having a portion thereofcomprised of sintered porous metal having a porosity of from about 1/2to 5 microns, said rear section having port means defined therein, saidfront section and said rear section having section channel meanslongitudinally defined therewithin and extending from said port means tosaid porous metal, thereby to provide in cooperation with said bodychannel means a fluid passageway between said porous metal and said stemmember, and further having an actuator rod means rearwardly extendingfrom said rear section through said body channel means, (C) heat sinkmeans located within said head member for conducting heat rearwardlyfrom forward portions of said head member, (D) spring means yieldinglybiasing said head member into a predetermined engagement with said bodymember, (E) retaining means limiting forward sliding movement of saidhead member relating to said body member, and (F) said body member andsaid head member coacting together to define therebetween an annularblow slot located where said head member extends from said body member,said blow slot being fully closed when said head member is slidablyretracted into said predetermined engagement with said body member, andbeing fully opened when said head member is slid forwards to the limitpermitted by said retaining means, there being a fluid passagewaybetween said blow slot and said body channel means, and further todefine cooperating outer surface portions for receiving a preformedliner thereover.
 9. A core rod adapted for blow molding a hollowthermoplastic article from a thermoplastic parison formed over apreformed thermoplastic liner on said core rod when said core rod isprovided with such a preformed thermoplastic liner, said core rodcomprising:a generally cup shaped body member having integral side andbottom walls defining a chamber with a mouth opposed to said bottomwall, mounting means integral with said bottom wall and extendingrearwardly therefrom and having a first channel longitudinally definedtherein and in said bottom wall which first channel communicates withsaid chamber, a head member having a front section and a rearsection,said rear section being telescopically slidably reciprocable insaid body member through said mouth, said front section terminating in ashoulder means for seating against mouth adjacent portions of said sidewalls for forming a blow slot when said shoulder means is unseatedrelative to said mouth, said front section being externally configuredas a core pin, a porous metal section having a porosity of from about1/2 to 5 microns located in said front section, which porous metalsection defines a surface portion of said front section, said frontsection and said rear section having a second channel meanslongitudinally defined in said head member and extending from a portmeans defined in said rear section to said porous metal section, saidfirst and said second channel means being in fluid communication witheach other, actuator means joining said rear section and arranged toextend reciprocably said head member relative to said body member toopen and close said blow slot, whereby, when negative pressure isexerted through said first channel with said blow slot closed, anegative pressure communication is provided at said porous metalsection, and, when a positive pressure is exerted through said firstchannel, and said blow slot is open, a positive pressure communicationis provided with said blow slot.
 10. The core rod as defined in claim 9wherein said head member includes a core pin support member whichcentrally and longitudinally extends within said front section and saidrear section.
 11. The core rod as defined in claim 10 wherein said headmember is spring biased into seating engagement with respect to saidbody member.
 12. The core rod as defined in claim 10 wherein said corepin support member is formed in part with an outer circumferentialsurface of a helical configuration whose land areas contact innersurface portions of said first section.
 13. A core rod assembly for blowmolding a hollow thermoplastic article from a preformed linercomprising:a body member; a core rod adjacent said body member andreciprocally moveable relative to said body member between a closedposition abutting said body member and an open position spaced from saidbody member; said core od having an internal fluid passageway thereinand having an outer surface adaptable for receiving said preformedliner; and a porous portion on said core rod in said outer surfacehaving a porosity of from about 1/2 to 5 microns, said porous portionproviding fluid communication means between said internal fluidpassageway and said outer surface of said core rod; and said internalfluid passageway being connectable with a fluid evacuation means forevacuating, through said porous portion and optionally said blow slotwhen open, the fluid between said hollow liner and said core rod whensaid liner is positioned on said core rod.